Overall: We were using a spreadsheet based system when we had a small internal team of testers. That team is now expanding, and the studio is also starting to rely on external QA sources to accomplish out testing goals. The spreadsheet system we were using was not able to scale to this level of work - enter DevTest. We made the conversion, and have not looked back since!

Pros: The product customization offered here is second to none. We had checked out close to 25 other similar products before finding one that correctly met our needs. We have teams that develop games for web based social platforms, and teams that develop games for mobile messaging apps. These games need to be accurately tested, and the tests need to be correctly linked to the environment that the tests were run in. Dev Test was the only product we found that was flexible enough to cater to these needs, and to do so in a structured, organized fashion which we were able to adapt to our work flow.
The customer care team has also been fantastic through the entire process. They helped us modify the tool to suit our needs, and were more then happy to get on service calls with us to answer any questions, explaining newly added functionality, or help with any required setup

Cons: The tool is complicated. I found the barrier to entry was a little high until I got the hang of it. The tool also has a tendency to lag when making major adjustments to test cases (image editing and such)